Cotton is a plant grown in the warmer climates of the world. It is a fibrous material used to make many types of products including, but not limited to, clothing, towels, paper, etc. When cotton is harvested, it is composed of two parts, (i) the fibrous material called lint, and (ii) the seed. The seed is attached to the lint and must be removed for the lint to be used to make yarn or other products. The process of removing the seed is called ginning.
There are two types of ginning, namely, roller ginning and saw ginning Extra long staple or long fiber length cottons are roller ginned. This is a gentle way of removing the seed as the lint and seed separate easily. Upland cotton is saw ginned. Saw ginning is a more aggressive procedure, which is needed as the seed is attached firmly to the lint.
The machine that performs saw ginning is called a gin stand. The gin stand consists of a gin saw mandrel, a gin breast, a doffing brush, an application roller, and an agitator or seed tube. Different manufacturers have different names for some of the parts, but the components are all basically the same.
The saw mandrel consists of multiple saw blades on a shaft with each saw blade separated by a spacer positioned between adjacent saw blades. The saw mandrel is threaded on each end and a nut is tightened to push the saws and spacers together and to keep them from moving. Saw mandrels vary in length by model and manufacturer. Saw mandrels are typically from 72.0 inches (in.) to 100.0 in. in length. The saw blades and spacers also vary in diameter and thickness. The saw blades typically have (i) a thickness ranging from about 0.036 in. to about 0.045 in. and (ii) a diameter of from about 12.0 in. to about 18.0 in. The spacers also vary in diameter and thickness. The spacers on any given saw mandrel are smaller in diameter than the saw blades. For example, one manufacturer's mandrel uses twelve-inch diameter saw blades with six-inch diameter spacers.
The gin breast consists of individual vertical members called ribs. The center to center measurement between the gaps in the ribs matches the center to center measurement between the saw blades on the saw mandrel for a particular gin stand. The gap between ribs may vary, but is typically from about 0.090 in. to about 0.125 in.
In the saw ginning process, cotton is grabbed by the teeth on the saw blades and pulled between the ribs. The gap between the ribs is smaller than the seed. Thus, the gin stand separates the cotton fiber from the cotton seed.
As ginning capacity has increased and seed size has been reduced due to new varieties of cotton, the gap between ribs has been getting smaller over the years. Although the center measurements vary with model and manufacturer, manufacturers have been required to reduce the center measurement in response to a smaller seed size. For example, one manufacturer uses a spacing of 0.5741 in. between centers (i.e., between centers of saw blades).
A saw mandrel is assembled by sliding a saw blade and a spacer onto a shaft, and repeating, until all of the saw blades and spacers are on the shaft. A nut is then placed on each threaded end of the shaft and tightened to push the saws and spacers together to keep them tight and to keep them from moving. A template the length of the mandrel with marks for correct spacing is placed on the saw cylinder to check spacing. If needed, the nuts are loosened and shims are intermittently added to match the template as closely as possible. Each saw blade is then individually bent (manually) with a fork bending tool to match each mark on the template. A mark is then drawn along the length of the cylinder at the position of the template. At this one point, the spacing should be correct on the saw mandrel. Although the cylinder (and saw blades positioned thereon) should be correct in this one point, each saw blade must be checked along the 360 degrees of each saw blade. This is needed as the saw blades may have a slight kink in them or an imperfection in one or more space blocks may cause the saw blades to wobble as it rotates in the gin stand. “Training” the saw blades is the process for straightening the blades.
Up until now, training of saw blades has been done with a manual and archaic procedure. Starting at the first blade, a dial indicator is put on the mark that was made with the template. The saw blade is then rotated and as the dial indicator moves to an unacceptable level the saw blade is manually bent with the fork saw training tool until the saw blade is in an acceptable range. This is repeated the entire 360 degrees of the saw blade. This procedure is repeated for each blade on the saw mandrel.
A slight variation of this manual procedure is using a pointer on the alignment mark and slightly off the blade. The saw blade is turned and trained by visual reference of the pointer to the wobble of the blade. Using the dial indicator is a much more accurate method of these two procedures. However, the problem even with the dial indicator method is the accuracy depends on the initial setup using the template. It is using a visual reference for each blade that must be very accurate for the dial indicator to give a true reading. This can be done, but is extremely time-consuming to complete one saw mandrel. Further, due to the time factor, the precise initially accuracy is often overlooked.
The gin operator or gin owner will not know the quality of the “training job” until the saw mandrel is installed in the gin stand. If the saw blades are rubbing the ribs, the saw blades rubbing will have to be manually trained in the gin stand to be clear of the ribs. Rubbing saw blades shorten the life of the saw blades and ribs, and if the rubbing is severe enough, the rubbing can be a fire hazard as cotton is extremely flammable. Further, the horsepower required to turn the mandrel is increased due to friction, and the capacity of the gin stand is decrease.
What is needed in the art is an apparatus and method for automatically training saw blades along a saw mandrel so as to eliminate the inefficient, time-consuming process of manually training saw blades along a saw mandrel.